Our president's first to get in newly-developed softer bed (4-6)
I believe the answer is:
four-poster
'bed' is the definition.
(four-poster is a kind of bed)
'our president's first to get in newly-developed softer' is the subsidiary indication.
'first' indicates taking the first letters.
'to get in' means one lot of letters goes inside another.
'newly-developed' indicates anagramming the letters.
The first letter of 'presidents' is 'p'.
'our'+'p'='ourp'
'softer' anagrammed gives 'foster'.
'ourp' put inside 'foster' is 'fourposter'.
(Other definitions for four-poster that I've seen before include "Style of bed" , "Type of bed" , "Imposing item of bedroom furniture" , "Curtained bed" , "Canopied bed" .)